Alok Roy

UHV/EHV Level

HV/MV Level

LV Level

The Concept of a power gridThe Concept of a power grid

Evolution of IndianEvolution of Indian Power GridPower Grid• Phenomenal expansion since Independence

Generation : 1349 MW 101,866 MW (in 1947) (in 2001)

Grid :

Local grid – at the time of Independence.

State Grids – emerged in 1960s.

Regional Grids – in 1970s.

Five Regional Grids – Northern, Western, Southern,

Eastern & North-eastern

National Grid – under progress.

Power Scenario – at a GlancePower Scenario – at a Glance• Existing• Installed capacity - 101,866 MW Coal – 71%

Hydro – 25 Nuclear &

others – 4%• Peak demand

Peak power - 78,000 MW Energy (average) - 1395 MU/day

• Availability Peak power - 68,000 MW Energy (average) - 1288 MU/day

• Shortage Peak power - 10,000 MW (12.8%) Energy - 107 MU/day (7.7%)

OPERATION OF LARGE INTERCONNECTED OPERATION OF LARGE INTERCONNECTED SYSTEM W.R.T. INDIAN CONTEXTSYSTEM W.R.T. INDIAN CONTEXT

• Indian Power System is ‘Large’ geographically and

very wide-spread in terms of generation and load locations

• Various electrical regions characteristically different w.r.t. the generation mix, system size, load factors, grid parameters etc.

• Evolution from state level entities to the present regional system still has inadequacies in true sense of ‘power system’

• Almost ‘Stiff’ power system elements (e.g. most Indian generators) do not rise to occasion at the time of parameter variation or contingency.

• In absence of higher order control (in terms of hierarchy) such as the AGC and near-absence of parameter based local variations in our control techniques, technical solution can not be ensured presently for steady-state operation. Dynamic and transient modes shall continue to be vulnerable areas.

Frequency of Northern Region for 03-04-2002

48.50

49.00

49.50

50.00

50.50

51.00

51.50

Time

Fre

qu

en

cy (

Hz)

Load Curve of Northern Region for dated 21-04-2002

12000

13000

14000

15000

16000

17000

18000

19000

Time

Lo

ad in

MW

47.00

48.00

49.00

50.00

51.00

52.00

53.00

54.00

55.00

Fre

qu

ency

in H

z

Load (MW) Frequency (Hz)

• BIGGER CHALLENGE TO SYSTEM OPERATORS compared to that for operators of perfect or near-perfect power system in developed countries

• WHAT NEXT?

• COMMERCIAL MECHANISM IS THE ONLY ANSWER

•Result ??

• B.1 REACTIVE POWER CONTROLREACTIVE POWER CONTROL

• LOW VOLTAGE

• Accountability of Load Power factor missing at present• Severe inadequacy in compensation at the point of

drawal• No or low redundancy in transmission and sub-

transmission levels• Overloading of distribution circuits in part or full• Lumping of capacitive compensation, sometimes at

higher voltages rather than at distribution levels• ‘Mental block’ of generation engineers to generate MVAR

upto rated value of machines

• Movement of reactive power over long distances - physically and electrically

• Low voltages, sometimes severe, even on EHV sub-stations, more accentuated when coupled with low grid frequency

Fall-out:

• Low output and in-efficient working of voltage sensitive equipment including certain generating station auxiliaries, high system losses, tripping of healthy transmission lines on distance-relay load encroachment at times, burning of certain equipment due to over-current etc.

NORTHERN REGIONAL LOAD DESPATCH CENTRE400 kV VOLTAGE PROFILE IN NORTHERN REGION AT 15:00 HRS ON 08.07.99

402

385

351 352

335

360 361

300

350

400

450

Singrauli Kanpur Ballabgarh Dadri Panipat Moga Jaipur

400 kV BUS

BU

S V

OLTA

GE

(kV

)

Capability Curve of a typical 210 MW BHEL Generator

Capability Curve of a typical 500 MW BHEL Generator

• B 2. REACTIVE POWER CONTROLREACTIVE POWER CONTROL (Contd......)

• • HIGH VOLTAGE:

• Though not encountered as frequently and as severely as Low Voltage cases/spreads in the country, but are caused mainly due to

• Underloaded system/sub-system elements

• Non-switched capacitors/banks resulting in lumped surplus MVAR in case of load drop

• Even bigger ‘Mental Block’ of generation engineers to absorb MVAR upto machine rating, usually ‘stiff’ AVR for cross-over to left.

• Non-provision of certain switched/non-switched shunt reactors on EHV/UHV lines or bus reactors

• High Voltages in the affected pockets, sometimes even

at EHV/UHV Levels, more accentuated when coupled with high frequency conditions in the grid.

• Fall-out: Tripping of overvoltages-sensitive elements

including trunk EHV/UHV Lines, dielectric failures/accelerated ageing of equipment, avoidable

power loss, common failure of heating elements etc.

Power Scenario – at a GlancePower Scenario – at a Glance All figs. are in MW

Region Peak Installed Peak Demand Capacity

Surplus/Deficit

Northern 21,000 27, 000 - 2,100Western 25,000 30,800 - 4,500Southern 20,400 24,800 - 2,600Eastern 7,800 15,700 + 2,000North-eastern 950 1,800 - 25

• Limited exchange of power between Regions --- Main reasons:

– Inadequate interconnectors, especially from Eastern Region– Lack of proper Commercial and administrative mechanisms

Demand-Availability Scenario – by Demand-Availability Scenario – by 2011-122011-12

Assumptions: • Demand – as per 16th Electric Power Survey Report (EPS).• Capacity addition – as per information available from MoP & CEA.• Generation availability (average) – 75%.

All figs. are in MW

Region Demand Installed Availability Deficit/ Capacity Surplus

Northern 49000 52354 39265 - 9735

Western 46000 53343 40007 - 5993

Southern 42000 50075 37556 - 4444

Eastern+North-east 19000 44275 33206 + 14206

Power Transfer Envisaged from ER and NER by 2012

DEVELOPMENT OF NATIONAL GRID

NER

ER

NR

WR

SR

EXISTING

500MW

MW1000

MW500

GAZUWAKA

CHANDRAPUR

VINDHYACHAL

SASARAM

UNDERCONST.

EXISTING

400 kV

220 kV

BONGAIGAONBIRPARA

MALDA

KORBA BUDHIPADAR

KOLHAPUR

BELGAUM

U.SILERU

BALIMELA

DEHRISAHUPURI

MALANPUR

AURAIYA

PHASE-I(By 2002)

Back

ROURKELA

RAIPUR HIRMA

TALCHER

JAIPUR

NER

ERWR

NR

SR

B'SHARIF

ALLAHABAD

SIPAT

GAZUWAKA

JEYPORECHANDRAPUR

SINGRAULI

VINDHYA-

1000MW

500MW

LUCKNOW

CHICKEN NECK

KRISHNA

TEESTA

MISA

KATHAL-GURI

LEGEND

765 KV LINES

400 KV LINES

HVDC B/B

HVDC BIPOLE

EXISTING/ X PLAN

ZERDA

HISSAR

BONGAIGAON

DEVELOPMENT OF NATIONAL GRID

KOLHAPUR

NARENDRA

KAIGA

MANGALORE

PONDA

IX PLAN

MARIANI

N.K.

KAHALGAON

RANGANADI

SEONI

CHEGAON

BHANDARA

DEHGAM

KARAD

LONIKAND

VAPI

GANDHAR/

TALA

BANGLA

BALLABGARH A'PUR(DELHI RING)

BANGALORE

KOZHIKODE

COCHIN

KAYAMKULAM

TRIVANDRUM

PUGALUR

KAYATHAR

KARAIKUDI

CUDDALORE

SOUTH CHENNAI

KRISHNAPATNAM

CHITTOOR

VIJAYAWADA

SINGARPET

PIPAVAV

LIMBDI

KISHENPUR

DULHASTI

WAGOORA

MOGA

URI

BHUTAN

RAMAGUNDAM

RAVI

JULLANDHAR

DESH

NAGAR

VARANASI

/UNNAO

M'BAD

PURNEA

KORBA

NAGDA

SILIGURI/BIRPARA

TEHRI

MEERUT

BHIWADI

BINA SATNA

MALANPURSHIROHI

KAWAS

PHASE - II(By 2007)

SIRSI

CHAL

JETPURAMRELI

BOISARPADGHE

DHABOL

KOYNA

/BARH

G'PUR

HOSUR

Back

ROURKELA

RAIPUR HIRMA

TALCHER

JAIPUR

NER

ERWR

NR

SR

B'SHARIF

ALLAHABAD

SIPAT

GAZUWAKA

JEYPORECHANDRAPUR

SINGRAULI

VINDHYA-

1000MW

500MW

LUCKNOW

DIHANG

CHICKEN NECK

KRISHNA

TEESTA

TIPAIMUKH

BADARPUR

MISA

DAMWE

KATHAL-GURI

LEGEND

765 KV LINES

400 KV LINES

HVDC B/B

HVDC BIPOLE

EXISTING/ X PLAN XI PLAN

ZERDA

HISSAR

BONGAIGAON

DEVELOPMENT OF NATIONAL GRID

KOLHAPUR

NARENDRA

KAIGA

MANGALORE

PONDA

IX PLAN

MARIANI

N.K.

KAHALGAON

RANGANADI

SEONI

CHEGAON

BHANDARA

DEHGAM

KARAD

LONIKAND

VAPI

GANDHAR/

TALAARUN

BANGLA

BALLABGARH A'PUR(DELHI RING)

BANGALORE

KOZHIKODE

COCHIN

KAYAMKULAM

TRIVANDRUM

PUGALUR

KAYATHAR

KARAIKUDI

CUDDALORE

SOUTH CHENNAI

KRISHNAPATNAM

CHITTOOR

VIJAYAWADA

SINGARPET

PIPAVAV

LIMBDI

KISHENPUR

DULHASTI

WAGOORA

MOGA

URI

BHUTAN

RAMAGUNDAM

SATLUJRAVI

JULLANDHAR

DESH

NAGAR

VARANASI

/UNNAO

M'BAD

PURNEA

KORBA

NAGDA

SILIGURI/BIRPARA

PHASE - III

TEHRI

MEERUT

BHIWADI

BINA SATNA

MALANPURSHIROHI

KAWAS

AMRAVATI

AKOLA

(By 2012)

AGRA

SIRSI

CHAL

JETPURAMRELI

BOISARTARAPUR

PADGHE

DHABOL

KOYNA

/BARH

G'PUR

HOSUR

NeedNeed forfor NationalNational GridGrid• Uneven disposition of energy resources

Major Hydro resources in NER & NRCoal reserves mostly in Bihar/Orissa/West Bengal

Cost of power transmission (1.11 cents/kwh) lower than cost of fuel transportation (3.33 cents/kwh).

• Some Regions are no longer Self-sufficient

Major resources in SR exhausted In NR, mainly hydro resources having long gestation period

• Unbalanced Growth of different Regions

Some regions are surplus and some are deficit.

• Optimisation of generation capacity additionUtilising time diversitySpinning reserve optimisation

Development of National Grid – Major Development of National Grid – Major ConsiderationsConsiderations

• Development in a phased manner – commensurate with

generation/ load growth

• Conservation of Right-of-Way - especially in areas with scarcity of

ROW ---- viz. area near hydro, chicken-neck area, forest area,

town etc.

In forest area with rich flora & fauna, construction of line with

high towers ---- no forest cutting required.

• Minimisation of transmission cost - immediate as well as long-term basis.

• Flexible enough to accommodate change in load-generation pattern.

Plan for National GridPlan for National Grid PHASE-I (By 2002):

Interconnection through HVDC Back-to-Back links-

North – West: 500MW Vindhyachal Back-to-Back Under

West – South: 1000MW Chandrapur Back-to-Back Opera-

East – South: 500MW Gazuwaka Back-to-Back tion East – North: 500MW Sasaram Back-to-Back – expected by

(AC line of this project in operation 2002

--- transferring 350 MW in radial mode)

With the completion of Sasaram HVDC Back-to-back link, framework of National Grid would be completed.

Plan for National GridPlan for National GridPHASE-II (By 2007):

• High capacity “Transmission highways” envisaged alongwith major generation projects-

East-South 2000 MW HVDC bipole between Talcher-Kolar - 2003.Augmentation of Gazuwaka HVDC back-to-back by 500MW - 2004. East – North High capacity 400 kV link from Tala to Delhi - 2004.2500 MW HVDC bipole between Hirma – Jaipur- 2005 East – West 400kV AC link between Rourkela and Raipur –2003400kV AC link between Hirma and Raipur & Sipat - 2005..

MAP

Plan for National GridPlan for National Grid

PHASE-III (By 2012):

Establishment of a ring of 765kV lines traversing across Northern, Western and Eastern Regions

Construction of various sections of Ring progressively along with major generation projects viz. Barh, Kahalgaon, North Karanpura etc.

Strengthening of East-South interconnection through another 2500MW bipole

MAP

National Grid: Cost-benefit analysisNational Grid: Cost-benefit analysisCost

Investment required Rs. 23,000 crores

Benefits

Reduction in capacity addition requirement by about 13750 MW--- hence saving on

investment of Rs. 55,000 crore. (due to peak time diversity and saving in spinning

reserve)

Transmission highway would enable setting up of large pit head stations having

lower cost of energy

Savings on account of this - Rs. 9000 crores per annum.

In addition, Nation’s investment towards fuel transportation infrastructure could be

avoided.

Better overall hydro-thermal mix

Very low for ER and WR ( ER – 15 : 85, WR - 17 : 83 ) – affecting grid

operation

With National Grid, it would become 33 : 67 on all India basis. .